Chorionic villus sampling - series: MedlinePlus Medical Encyclopedia

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Chorionic villus sampling - series

Normal anatomy

Chorionic villi are microscopic projections that line the chorion, the outermost layer of the embryonic sac. Surgeons sample these projections for genetic testing because they contain the same genetic material as a fetus.

If you are at risk for delivering a baby with genetic abnormalities, your health-care provider may recommend this prenatal test, which is performed at 10 to 12 weeks gestation to find out a fetus' genetic makeup.

Update Date: 5/2/2008

Updated by: Linda Vorvick, MD, Seattle Site Coordinator, Lecturer Maternal & Child Health, Pathophysiology, MEDEX Northwest Division of Physician Assistant Studies, University of Washington School of Medicine; and Susan Storck, MD, FACOG, Clinical Teaching Faculty, Department of Obstetrics and Gynecology, University of Washington School of Medicine; Chief, Eastside Department of Obstetrics and Gynecology, Group Health Cooperative of Puget Sound, Redmond, Washington. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

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